The production method of the present disclosure includes heat-treating a material mixture containing a compound containing Y, a compound containing Gd, NH.sub.4α, Liβ, and Caγ.sub.2 in an inert gas atmosphere. The compound containing Y is at least one selected from the group consisting of Y.sub.2O.sub.3 and Yδ.sub.3, and the compound containing Gd is at least one selected from the group consisting of Gd.sub.2O.sub.3 and Gdε.sub.3. The material mixture contains at least one selected from the group consisting of Y.sub.2O.sub.3 and Gd.sub.2O.sub.3, and α, β, γ, δ, and ε are each independently at least one selected from the group consisting of F, Cl, Br, and I.

Disclosed are a composite oxide which is capable of maintaining a large volume of pores even used in a high temperature environment, and which has excellent heat resistance and catalytic activity, as well as a method for producing the composite oxide and a catalyst for exhaust gas purification employing the composite oxide. The composite oxide contains cerium and at least one element selected from aluminum, silicon, or rare earth metals other than cerium and including yttrium, at a mass ratio of 85:15 to 99:1 in terms oxides, and has a property of exhibiting a not less than 0.30 cm.sup.3/g, preferably not less than 0.40 cm.sup.3/g volume of pores with a diameter of not larger than 200 nm, after calcination at 900° C. for 5 hours, and is suitable for a co-catalyst in a catalyst for vehicle exhaust gas purification.

A method for preparing lanthanum carbonate tetrahydrate and a product thereof. The lanthanum carbonate tetrahydrate is prepared by reacting lanthanum oxide and acetic acid with potassium carbonate or potassium bicarbonate or ammonium bicarbonate to prepare lanthanum carbonate octahydrate, and drying the lanthanum carbonate octahydrate. Compared with the lanthanum carbonate tetrahydrate in the prior art, the prepared lanthanum carbonate tetrahydrate has a characteristic spectral peak on a terahertz spectrum, and has excellent dissociation and dissolution characteristics of lanthanum ions.

A method for preparing lanthanum carbonate tetrahydrate and a product thereof. The lanthanum carbonate tetrahydrate is prepared by reacting lanthanum oxide and acetic acid with potassium carbonate or potassium bicarbonate or ammonium bicarbonate to prepare lanthanum carbonate octahydrate, and drying the lanthanum carbonate octahydrate. Compared with the lanthanum carbonate tetrahydrate in the prior art, the prepared lanthanum carbonate tetrahydrate has a characteristic spectral peak on a terahertz spectrum, and has excellent dissociation and dissolution characteristics of lanthanum ions.

A method for extracting scandium from scandium-containing materials, said method comprising: re-slurring of a cake of a scandium-containing material with a mixture of sodium carbonate and sodium bicarbonate, carbonization leaching of the scandium-containing material with the mixture of sodium carbonate and sodium bicarbonate in one stage, filtration of the leached scandium-containing material and the precipitation of a scandium concentrate. The carbonization leaching of the scandium-containing material is carried out with a mixture of sodium carbonate and sodium bicarbonate having a Na2CO3 concentration of 130-350 g/dm.sup.3 and a NaHCO3 concentration of 2-100 g/dm.sup.3 at a pH value in the slurry of 9.5-11.0 and a temperature of 20-90° C. For maintaining the required pH value in the slurry, the slurry is gassed with a CO2-containing gas-air mixture. The scandium concentrate is extracted from the filtrate resulting from the leaching process in one stage by treating said filtrate with an alkaline solution.

A method for extracting scandium from scandium-containing materials, said method comprising: re-slurring of a cake of a scandium-containing material with a mixture of sodium carbonate and sodium bicarbonate, carbonization leaching of the scandium-containing material with the mixture of sodium carbonate and sodium bicarbonate in one stage, filtration of the leached scandium-containing material and the precipitation of a scandium concentrate. The carbonization leaching of the scandium-containing material is carried out with a mixture of sodium carbonate and sodium bicarbonate having a Na2CO3 concentration of 130-350 g/dm.sup.3 and a NaHCO3 concentration of 2-100 g/dm.sup.3 at a pH value in the slurry of 9.5-11.0 and a temperature of 20-90° C. For maintaining the required pH value in the slurry, the slurry is gassed with a CO2-containing gas-air mixture. The scandium concentrate is extracted from the filtrate resulting from the leaching process in one stage by treating said filtrate with an alkaline solution.

Disclosed are methods to produce Thermal Barrier Coating (TBC) products using materials recycled from TBC waste. These methods include ways to produce zirconium and rare earth chemicals and raw materials appropriate for producing TBC materials.

Disclosed are methods to produce Thermal Barrier Coating (TBC) products using materials recycled from TBC waste. These methods include ways to produce zirconium and rare earth chemicals and raw materials appropriate for producing TBC materials.

The present disclosure discloses a method for preparing rare earth oxide by recycling ammonia and carbon, comprising the steps of: (1) heating raw materials containing a first rare earth carbonate and a first rare earth oxide with microwave and calcining at 500-1000° C. for 20-120 min to obtain a second rare earth oxide and carbon dioxide; (2) reacting carbon dioxide with a first ammonia water to obtain a precipitant; (3) reacting the precipitant with rare earth chloride to obtain a second rare earth carbonate and ammonium chloride wastewater. In the method, calcination time is short, rare earth recovery rate, utilization rate of ammonia and carbon resources are high. The present disclosure also provides a use of a rare earth oxide in shortening calcination time and/or increasing rare earth yield.

The present disclosure provides for compositions, methods of making compositions, and methods of using the composition. In an aspect, the composition can be a reactive material that can be used to split a gas such as water or carbon dioxide.